Continuum Arm Control with Constraints on the Driving Forces via Fractional Order Models

The paper presents an extension of the Circle Criterion for the dynamic models of the continuum robots. This technique is applied to the control of the fractional order model system with constraints of the driving forces. It is demonstrated that the stability of the closed loop control system requires that the arm frequency plot does not intersect the circle of driving constraints. It is shown that nonlinear components worsen the stability of the system. The proposed methods are illustrated by numerical simulation and experimental tests.